Objectives: During osteosynthesis of a fracture patients are exposed to the primary radiation of an X-ray image and scattered (secondary) radiation. The primary objective was to measure the amount of scattered radiation at the thyroid, breast tissue, and gonads of patients undergoing primary osteosynthesis of acute fractures. The secondary objective was to calculate the effective dose caused by scattered radiation. Methods: In this multicenter prospective observational case series patients undergoing a primary osteosynthesis of an acute fracture of hand/wrist, shoulder, ankle, knee, or hip were included. Three dosimeters were attached to the patient at the level of the thyroid, breast and gonads. Scattered radiation doses were corrected for the average background radiation per hospital per day. Results: A total of 205 patients were included between March 6, 2017 and June 18, 2018; 49 (24%) had a hand/wrist fracture, 37 (18%) a shoulder fracture, 47 (23%) an ankle fracture, 35 (17%) a knee fracture, and 37 (18%) a hip fracture. In 32–39% of all patients undergoing primary osteosynthesis effective scattered doses was detected. The highest measured median effective dose was 60.43 µSv (P₂₅–P₇₅ 33.84–100.76) at the gonads during hip osteosynthesis. Conclusions: The results of this study show that scattered radiation is detectable in a third of patients undergoing an osteosynthesis. However, both effective doses due to direct radiation and scattered radiation are low. Advances in knowledge: This is the first study that presents that no radiation protection for patients undergoing an osteosynthesis is necessary.